A busy highway bridge that spans the Mississippi River just northeast of Minneapolis collapsed during rush hour Wednesday, sending a school bus, other vehicles and tons of concrete crashing into the water.

The entire span of the Interstate 35W bridge collapsed about 6:05 p.m. A tractor-trailer caught fire, and flame and black smoke billowed into the sky.

Local media reported 20 to 30 injuries but initially no deaths. NBC News reported that every Minneapolis ambulance had been requested to the scene.